The present invention relates to an insecticidal composition comprising an active amount of at least one pyrethroid, at least one UV absorbing agent and at least one anti-oxidant, and its use for controlling flying and crawling insects.
The insecticidally effective components of pyrethrum and its synthetic analogues, which are derived from the structure indicated in the following, are designated as pyrethroids. The main active substances in pyrethrum are the cinerins I and II, the pyrethrins I and II and the jasmolins I and II (R ompps Chemie-Lexikon, 8th edition (1987), page 3413).
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______________________________________ Pyrethrin I: R.sup.1 = CHCH.sub.2, R.sup.2 = CH.sub.3 Pyrethrin II: R.sup.1 = CHCH.sub.2, R.sup.2 = COOCH.sub.3 Cinerin I: R.sup.1 = R.sup.2 = CH.sub.3 Cinerin II: R.sup.1 = CH.sub.3, R.sup.2 = COOCH.sub.3 Jasmolin I: R.sup.1 = C.sub.2 H.sub.5, R.sup.2 = CH.sub.3 Jasmolin II: R.sup.1 = C.sub.2 H.sub.5, R.sup.2 = COOCH.sub.3 Allethrin: R.sup.1 = H, R.sup.2 = CH.sub.3 ______________________________________
Pyrethrum is obtained from the dried flower heads of various pyrethrum or chrysanthemum species by pulverization or extraction and contains as main active substances pyrethroids such as pyrethrins, cinerins and jasmolins. Apart from nicotine, pyrethrum is the strongest vegetable insecticide; however, its effectiveness is reduced by sunlight and heat (R ompps Chemie-Lexikon, 8th edition (1987), page 3414). The lack of stability, but also the high price of natural pyrethroids led to the development of numerous synthetic derivatives.
Pyrethroids are generally used as isomer mixtures. They have been used for a long time as insecticides, in particular against common houseflies, cockroaches or blackbeetles and other household vermin, moths, corn weevils, mosquitoes, garden and greenhouse parasites, hay worms in viticulture and boll-weevils. Particularly, the natural pyrethroids distinguish themselves by a rapid so-called knock-down effect, i.e. the insects are certainly paralyzed rapidly, but only temporarily, and they recover again. The oxidative detoxication metabolism of the insects is responsible for this undesired effect.
Due to the great instability of the pyrethroids to air and light, numerous attempts have already been made to stabilize pyrethroids and to prolong their effectiveness.
Pyrethrum Post 11(4), 135-7, 51 and J. Agr. Food Chem, 20(2), 313-15 disclose the stabilizing of pyrethrins and allethrin by the addition of an antioxidant and a UV absorbing agent in a mineral oil formulation. While non-stabilized formulations are destroyed almost completely within 4 hours, the combination of an oxidant and a UV absorbing agent results in a considerable stabilization of the pyrethroids for at least 4 hours and more.
Aromatic ketones in which two aromatic rings are directly bonded to an oxo group, e.g. benzophenone derivatives, and esters of aromatic acids, such as esters of substituted benzoic acids are mentioned. The used antioxidants have an OH group, which is directly bonded to an aromatic ring, and at least 14 carbon atoms such as 4-methyl-2,6-di-tert.-butyl phenol or 2,6-dioctadecyl-p-cresol.
US-A-3-506-613, WO-A-86/03374, EP-A-147 947, DE-A-2 615 646 and GB-A-2 058 569 describe various insecticidal compositions on pyrethroid basis, which contain antioxidants and customary UV absorbing agents for stabilizing the pyrethroids. 2,6-di-tert.-butyl-4-methyl phenol, 2,6-dioctadecyl-p-cresol, butylated hydroxy toluene, alkylated phenols, tert.-butyl hydroquinone, butylated hydroxy anisoles, ethoxy chin, ascorbic acid, their salts and derivatives and propionic acid salts are used as antioxidants. However, the stability of these compositions is not satisfactory.
It is the object of the present invention to provide an insecticidal composition with improved long-term effect.